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| Titel |
Isoprene in poplar emissions: effects on new particle formation and OH concentrations |
| VerfasserIn |
A. Kiendler-Scharr, S. Andres, M. Bachner, K. Behnke, S. Broch, A. Hofzumahaus, F. Holland, E. Kleist, T. F. Mentel, F. Rubach, M. Springer, B. Steitz, R. Tillmann, A. Wahner, J.-P. Schnitzler, J. Wildt |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 2 ; Nr. 12, no. 2 (2012-01-20), S.1021-1030 |
| Datensatznummer |
250010545
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| Publikation (Nr.) |
 copernicus.org/acp-12-1021-2012.pdf |
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| Zusammenfassung |
| Stress-induced volatile organic compound (VOC) emissions from transgenic
Grey poplar modified in isoprene emission potential were used for the
investigation of photochemical secondary organic aerosol (SOA) formation. In
poplar, acute ozone stress induces the emission of a wide array of VOCs
dominated by sesquiterpenes and aromatic VOCs. Constitutive light-dependent
emission of isoprene ranged between 66 nmol m−2 s−1 in
non-transgenic controls (wild type WT) and nearly zero
(<0.5 nmol m−2 s−1) in isoprene emission-repressed plants (line RA22),
respectively. Nucleation rates of up to 3600 cm−3 s−1 were
observed in our experiments. In the presence of isoprene new particle
formation was suppressed compared to non-isoprene containing VOC mixtures.
Compared to isoprene/monoterpene systems emitted from other plants the
suppression of nucleation by isoprene was less effective for the VOC mixture
emitted from stressed poplar. This is explained by the observed high
efficiency of new particle formation for emissions from stressed poplar.
Direct measurements of OH in the reaction chamber revealed that the steady
state concentration of OH is lower in the presence of isoprene than in the
absence of isoprene, supporting the hypothesis that isoprenes' suppressing
effect on nucleation is related to radical chemistry. In order to test
whether isoprene contributes to SOA mass formation, fully deuterated
isoprene (C5D8) was added to the stress-induced emission profile
of an isoprene free poplar mutant. Mass spectral analysis showed that,
despite the isoprene-induced suppression of particle formation, fractions of
deuterated isoprene were incorporated into the SOA. A fractional mass yield
of 2.3% of isoprene was observed. Future emission changes due to land use
and climate change may therefore affect both gas phase oxidation capacity
and new particle number formation. |
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